Production of alpha-halogenated keto acids



. material phases.

Patented Mar. 19, 1946 1 UNITED STATE s PATENT OFFICE PRODUCTION OF ALP KETO A HA-HALOGENATED cms No Drawing. Application October 10, 1944,

Serial No. 558,073

8 Claims. (Cl. 260-406) The present invention relates to the production of alpha-halogenated keto acids. More particularly the present invention relates to a novel process for the production of alphaehalogenated keto acids from unsaturated fats, esters, and fatty acids.

In application Serial No. 511,594, filed November '24, 1943, there are disclosed various alphahalogenated keto fatty acids and a process 'for preparing them involving halogenating keto fatty acids. As thus pointed out, such a halogenation tends to produce a, '-dihalo compounds and only under conditions of restrained halogenation is it possible to confine the same to only one alpha carbon to a relatively small extent. a e

In accordance with the present invention, how ever, it has been discovered that if the unsaturated fatty acids are treated with hypohalous acids, 1. e. hypochlorous and hypobromous acids,

to produce halo hydrin acids, the halo hydrin acids may then be oxidized under the conditions set forth in U. S. application Serial No. 467,810, filed December 3, 1942, to mono halo'keto acids in quantitative yields.

Accordingly. it is 'an object of this invention to provide a readily-controlled process for coninvention, there may be employed any fatty acids containing fatty chains of 8 or more carbon atoms and having an olefine linkage preferably separated from the carboxyl carbon by at least 2 carbon atoms in the chain and fatty materials containing such acids in a form capable of being readily'con'verted to'soaps so that they may be brought into intimate contact inaqueous solution with the hypohalous acid. The fatty chains contained in the starting materials to be processed in accordance with this invention may contain one or more unsaturated linkages. Preferably when more than one unsaturated linkage is present, they are separated by at least two carbon atoms inthe chain as closer proximity of the double bonds gives rise to the formation of closely adjacent hydroxy groups which are likely to promote oxidation and/or hydrolytic scission at these points. Starting materials con,-

taining-closely spaced double bonds willresult in somewhat reduced yields of 'keto fatty substances, sincethe keto compounds resulting from theoxidation of the hydroxyl groups in these configurations tend to be oxidatively and/or l5 hydrolytically split in the vicinity of the keto verting olefinic fatty. substances to the corresponding mono halogenated keto. substances.

A further object .is to obtain commercially practical yields of mono halogenated keto fatty and then treating the halo hydrin compounderides may be 'used.';In fact, any fatty materialwith an aqueous chromic acid solution at moderate temperatures so as to oxidize the hydroxy groupings in the -fatty material to form keto groupings. The water contained in the aqueous chromic acid solution causes the formation of two separate phases, one containing the chromic acid, and the othercontainin'g the fatty material, thus efiectively regulating the progress of the reaction and avoiding oxidative scission of' the fatty material 'even at somewhat elevated temperatures.- During the course of the reaction.

the mixture is vigorously agitatedto bring. about intimate contact of the chromic acid and fatty When the reaction is com-'- pleted, the resulting halogenated keto fatty ma-' terials are separated from the spent chromic acid solution and are purified.

As starting materials in the process of this groups.

The fatty acids suitable for use as starting materials in the practice of this invention are exemplified in .oleic acid, palmitoleic, myristoleic, erucic and other like acids. In place of the acids themselves, mixtures of acids and/or acid 'glyccapable of being saponified. either during the reaction to form thihal'o hydrinacid' or prior to the reaction is .suitable for use as'a starting material. Unsaturated acids havingzmore than one double bond such as linoleic and linolenic I and hydroxy unsaturated acids-such asricinoleic may also be used although since these commonly occurring acids have their double bonds in close proximity the yields of halogenated keto acids are somewhat low. I

Referring to the production of the halo hydrin acids from the fatty acids, preferably the. fatty acids are initially converted to a-potassium or sodium soap by admixture with an aqueous solution of sodium or potassitun hydroxide.

Thereafter chlorine or' bromine is passed into the resulting soapy solution while cooling, the chlorineor bromine being used in slight excess, 1. e. up to about 25%. The excess chlorine or bromine is then destroyedv as by the addition of sodium hydrin acid is oxidized to the halogenated keto acid as hereinafter 'set forth. 1

Referring to the aqueous-chromic acid oxidizing reagent, this may conveniently be an aqueous solution of NazCrzO-1 and HzSOl. However, the chromic acid solution may be prepared from any other hexavalent' chromium compound such as CI'QQ; KzCrzOv or NazCrO4 and any other oxidation-stable mineral acid such as HNO; or HaPO4. The water content of the oxidizing reagent must be suiiiciently high to cause 'the'chromic acid to form a separate phase when mixed with the hydroxylated fatty material. In general. the

The halogenated ketonic fatty products when recovered are characterized by sharp melting points.

Specific examples of the practice of this invention will now be described, all parts given being by weight. The sodium dichromate referred to in the examples was in all cases the hydrate NazClzOm2Ha0. v

- Example I :57 g. of oleic acid were converted to the potase slum soap by stirring with a solution of 23 g. of

potassium hydroxide to 3 l..of water. After coolamount of sulfuric acid contained in the oxidizing reagent should be between about 25% and about 75% of the combined amounts of water and sulfuric acid present therein. The hexavalent chromium compound should preferably be present in approximately 10% excess over the' quantity stoichiometrically required to oxidize the fatty material to be treated; however, in those cases in which side reactions are to be expected-for instance in the treatment of materials containing closely spaced double bonds,

the excess should beincreased to 50% or higher. The optimum proportions are best determined by preliminary experiment on the particular fatty materialto be processed, bearing'in mind the general consideration abovesetfor'th.

In addition to the chromic acid, the oxidizing mixture may also have incorporated therewith a small amount of an oxidation resistant mutual solventfor the fatty material and thechromic acid, such as acetic acid. However, preferably the. solvent is used in a relatively small amount, insuflicient to cause the aqueous and fatty material phases to merge,

Referring to the oxidation'process, this is carried out by intimatelymixing and agitating the halo hydrin fatty starting material with the aqueouschromic acidsolut'ion. The agitation is continued throughout the duration of the reaction to avoid local stagnation and to insure ture is maintained sufficiently high to'effect the oxidation of the hydroxyl groups in the fatty material to keto groups at an economic rate but is not maintained'so' high asto causeoxidative scission of the fatty chains. In general ternperatures between about 20- and about 80 C.

- will accomplish these results depending on the nature of the fatty starting material. The length of time required for. the completion of the" reaction will vary with the nature of the starting ma-- terial, the composition of the oxidizing agent,

and thetemperature at which the reaction is conducted. Ingeneralbetween about 5 and about B-hours will be required:

At the conclusion of the; oxidation reaction,

the reaction'mixture is diluted with water. and

the oxidized fatty material is separated from the spent acids and salts- Thereafter the occluded acids and-salts are washed out of the oxidized; 7 fatty product by means of aqueous washing soluing to 5 a 10% excess of chlorine gas'was passed through the resulting soapy solution with stirring. After standing for 1 to 2 hours, the excess hypochlorous acid was destroyed by the addition of sodium bisulfite solution until litmus paper was no longer bleached and then the aqueous solution was carefully acidified with sulfuric acid. The fatty acids that separated were dissolved in benmile. This benzene solution was extracted with water until it was neutral. The moisture and sol-' vent were removed by distillation. The yield of contact between the aqueous chromic acid-phase and the fatty starting material. The temperationsfand the washed productis recrystallized by means of organiesolvents. The aqueous washing agent should preferably be slightly acid in order to prevent the formation of and to break up any complexes or soaps formed by the fatty material with the chromic ions resulting from the oxidation reaction. F y

The practice of this invention as above outlined results in excellent yields of halogenated .ketonic fatty products free of undesired lay-products.

product (a golden syrup) was 60 g. (91%). -Neutral equivalent 345; I. V. 0.6. To a suspension of 50 grams of the oleic acid chlorhydrin in cc.

of 50% aqueous sulfuric acid a solution of 15 grams of'sodium 'dichromate'in 35 cc. of water .was added with stirring over a period of V hour at 50-55 C." Stirring was continued at this temperature for 7 /2 hours more. The reaction mixture was diluted 'witha large volume of water. After two layers had formed, the upper oily layer was separated from the water layer. The oily layer was dissolved in 2 volumes of a petroleum solvent and this solution was then boiled with 2 parts-of 18% hydrochloric acid based on the weight of the oil for 1 hour. After removal of the aqueous acid layer, thepetroleum solvent was removed by distillation. The residual oil weighed 49grams, equivalent to a yield of 98%. Neutral equivalent 337. v Theory 337.

Example If zene solution was extracted with water until it was neutral. The moisture and solvent were removed by distillation. The yield of chlorohydrin acid was 58 g. (94%). To a suspension of 58 g. of the chlorohydrin acid in 290 cc.-.of 50% sulfuric 81d,13 solution of 12.8 g. of sodium dichromate injz'i' cc. 'of water was added with stirring over a period of hour at 50 to 55 C. Stirring was continued at this temperature for 7% hours and the solids collected on 'afllter. The solids were dissolved in a petroleum solvent and boiled with 18% hydrochloric acid for 1 hour. After removal of the water layer, the solvent was removed by distillation. The residual oil which weighed 56 g.-(9'7% yiefd) was dissolved in petroleum ether and chilled at -1'1 overnight. The solid was collected on a filter and reclailled. A

second crop was obtained. Total yield of recrystallized material was 40 g. Neutral equivalent 388. Theory 889.

taining a fatty chain of at least 8 carbon atoms with a. member of the group consisting of hypobromous and hypochlorous acids to produce a halo hydrin fatty acid and thereafter oxidizing the halo hydrin fatty acid with an aqueous chromic acid solution to an alpha mono halogenated keto acid.

-2. A process for the production of alpha mono halogenated keto acids which comprises reacting a water-soluble soap of an unsaturated higher fatty acid containing a fatty chain of at least 8 carbon atoms with a member of the group consisting of hypobromous and hypochlorous acids to produce a halo hydrin fatty acid and thereafter oxidizing the halo hydrin fatty acid to an alpha mono halogenated keto acid by reacting .the same with a hexavalent chromium compound in the presence of an oxidation-resistant mineral acid and in the presence of sufiicient water to insure maintenanceof an aqueous phase separate from the halo hydrin fatty acid.

3. A process for the production of alpha mono halogenated keto stearic acid which comprises.

reacting a water-soluble soap of oleic acid with a member of the group consisting of hypobromous and hypochlorous acids to produce a halo hydrin of stearic acid and thereafter oxidizing the halo hydrin stearic acid to alpha mono halogenated keto stearic acid by reacting the same with a hexavalent chromium compound in the presence of an oxidation-resistant mineral acid and in the carbon atoms with a member oi the group consisting of hynobromous and hypochlorous acids to produce a halo hydrin fatty acid and thereafter oxidizing the halo hydrin fatty acid by reacting the same with a hexavalent chromium compound in the presence of an aqueous solution of an oxidation-resistant mineral acid, the mineral acid being present to the extent of between and 75% based on the total weight of mineral acid and water present in the reaction mixture.

6. A process for the production of alpha mono halogenated keto stearic acid ,which comprises reacting a water-soluble soap of oleic acid with a member of the group consisting of hypobromous and hypochlorous acids to produce halo hydrin stearic acid and thereafter oxidizing the halo hydrin stearic acid to alpha mono halopresence of suflicient water to insure maintenance of an aqueous phase separate from the halo hydrin fatty acid.

4. A process for the production of alpha mono halogenated keto hehenic acid which comprises reacting a water-soluble soap of erucic acid with a member of the group consisting of hypobromous and hypochlorous acids to produce halo hydrin behenic acid and thereafter oxidizing the halo hydrin behenic acid to alpha mono halogenated keto behenic acid by reacting the same with a hexavalent chromium compound in-the presence of an oxidation-resistant mineral acid and in the resence of sufiicient water to insure maintenance of an aqueous phase separate from the halo hydrin fatty acid.

5. A process for the production of alpha mono halogenated keto acids which comprises reacting a water-soluble soap of an unsaturated higher fatty acid containing fatty chains of at least 8 genated keto stearic acid by reacting the same with a hexavalent chromium compound in the presence of an aqueous solution of an oxidationresistant mineral acid, the mineral acid being present to the extent of between 25 and 75% based on the total weight of mineral acid and water present in the reaction mixture.

- 7. A process for the production of alpha mono halogenated keto behenic acid which comprises reacting a water-soluble soap of erucic acid with a member of the group consisting of hypobromous and hypochlorous acids to produce halo hydrin beh'enic acid and thereafter oxidizing the halo hydrin behenic acid to alpha mono halogenated keto behenic acid by reacting the same with a hexavalent chromium compound in the presence of an aqueous solution of an oxidationresistant mineral acid, the mineral acid being present to the extent of between 25 and 75% based on the total weight of mineral acid and water present in the reaction mixture.

8. A process for the production of alpha mono halogenated keto acids which comprises dissolving a soap of an unsaturated higher fatty acid containing fatty chains of at least 8 carbon atoms in water, passing a halogen selected from the group consisting of chlorine and bromine into the soap-water solution to produce a halo hydrin fatty acid and thereafter oxidizing the halo hydrin fatty acid by reacting the sam with a hexavalent chromium compound in the presence of an aqueous solution of an oxidation-resistant I mineral acid, the mineral acid being present to the extent of between 25 and based on the total weight of mineral acid and .water present in the reaction mixture.

DONALD PRICE. FRANCIS J. SPRU'LES. 

